28 to 144Mc/s TransverterThe Transverter arangement I have opted for here is the very cheaply available unit which can be bought from the Ukraine for under £20. The transverter is very well constructed and it is simply not worth building a similar unit as the cost would be far greater. It is fitted inside the SP-38 box with the other ancillary items mounted on a large finned heat sink. Fortunately there was enough output from the IC-7300 RF unit via the new low pass filter (180mV PP) to drive the transverter to the stated full 10 watts output.All looking good, but, on connecting the spectrum analyser I found the 288Mc/s harmonic was only 30dB below the wanted signal, completely unacceptable, fortunately the fix for this is very simple but the output level, now clean is reduced to 5 watts which is no problem for me as I will be using a separate linear amplifier.The output filter in the transverter is a simple PI arrangement and the fix is to connect a 30pF miniature trimmer across the output capacitor, C40, this new trimmer is tuned to present the lowest output at 288Mc/s which was found to be at least 60dB below the wanted signal. The oscillator frequency was pretty close but I found that it could be brought right on to frequency with the addition of a small ceramic tube trimmer of about 3pF maximum (NB the minimum capacitance should be no more than 0.5pF) fitted across R4, which is effectively across the crystal itself. For additional frequency stability the crystal on the corner of the board can be covered with a piece of foam or polystyrene isolating it from temperature variations although at 5 watts output and such a large heat sink these should be very small as even running a continuous carrier over a long period of time the output device barely gets warm.

The pictures below show the Transverter Board, Heat Sink and the Final Completed Assembly.​